ASK TOM WHY.

Dear Tom, What is the record for the longest stretch...

What is the record for the longest stretch of nights when the temperature remained at or above 70 in Chicago? This question came to mind during that long spell of warm, humid nights this summer.

Kris Partain, Libertyville

Dear Kris,

A computer search of 129 years (1873-2001) of Chicago's official weather records reveals the city's temperatures remained continuously at or above 70(degrees) from June 20 through July 30, 1921 -- a 41-day span that comprises the longest sustained warm spell in Chicago weather history. The second-longest period: 32 days, July 12-August 12, 1916.

We've heard many complaints this summer about the duration of heat and humidity, but perceptions can be deceiving. The longest stretch of 70(degrees)-plus nighttime temperatures recorded so far this summer is a relatively meager four days: July 30-August 2 and again August 6-August 9.

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Tom Skilling is chief meteorologist at WGN-TV. His weather forecasts can be seen Monday through Friday on WGN News at noon and 9 p.m.